There are a number of safety issues which may arise while operating mobile construction equipment. For example, overhead electrical power lines present a serious electrocution hazard to personnel in a variety of industries. Overhead lines, typically uninsulated conductors supported on towers or poles, are the most common means of electrical power transmission and distribution, and are exposed to contact by mobile equipment such as cranes and trucks. Equipment contacting energized an overhead power line can conduct large amounts of current from the power line through the equipment and into the ground. This can cause electrocution, fire, and damage to both the equipment and the power line. Further, even if there is no conductive electrical path through the equipment to ground, the chassis of the equipment can be elevated to a high voltage, which then can be contacted by personnel who create a grounding path, causing serious electrical shock and burns. Industries where risk of these accidents is greatest include, but are in no way limited to, construction, mining, agriculture, and communication/public utilities. Most commonly, mobile cranes (including boom trucks) are involved in accidents involving power lines.
Methods of preventing dangerous contact of equipment with electrical power lines include de-energizing the power line, restricting equipment motion in proximity to power lines, use of a field observer to alert the operator of impending contact, insulating/electrically isolating the portions of equipment that could contact a power line, and physical barriers to prevent direct contact with an energized line. Because these techniques are expensive, disruptive, and/or lack flexibility, they are not practical in many circumstances. For example, over reliance on field observers is expensive. Further field observers have been shown to be less effective in preventing accidents because of poor viewing positions and distractions.
Accordingly, there is a need for an inexpensive, reliable and versatile sensor system that can detect and minimize hazards that are created by using equipment in proximity to power lines.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.